Modelling of induction motor loads in power‐system voltage stability studies

In planning an interconnected power network, it is very important to assess whether a voltage collapse occurs during a prefixed operating condition. However, it has been often found that voltage phenomena occur in a real system at a load condition different from the one predicted by simulation studies. One of the causes that makes the use of present procedures unreliable is the lack of adequate models for dynamic loads. To overcome this difficulty, the paper presents a practical approach which analyses the influence of dynamic load modelling on the voltage stability limits of interconnected power systems. Five different representations of induction motor loads are considered and the degree of accuracy of each model is investigated. Simulation studies on a sample power system clearly show that voltage stability limits can be strongly affected by the adopted representation.